1. Field of the Invention
This invention relates to an interruption-free power supply with a line-communicated, controlled rectifier, the input of which is connected to a supply network and the output of which is connected with the input of a self-commutating, controlled inverter, which supplies the network to be protected via filter means.
2. Description of the Prior Art
Interruption-free power supplies of the aforesaid type are disclosed, for example, by M. Meyer, "Self-Commutating Thyristor Converters", Siemens AG, 3. Edition, 1974, pages 228 to 235, or in Siemens-Zeitschrift vol. 47 (1973), pages 123 to 126. These interruption-free power supplies are used to protect consumers against failure of the supply network. In this connection, the above-mentioned filter means of the power supply is required to convert the square- or step-shaped a-c voltage formed by the inverter into a sinusoidal voltage, which is, in general, demanded by the network being protected. In the event of sudden load changes, for example, if the load connected to the network being protected is dumped, voltage peaks, which may exceed the tolerances of the network being protected may occur because of the energy stored in the filter means.
It is, therefore, an object of the present invention to provide an interruption-free power supply of the above type which is modified so as to reduce such overvoltages to an extent that they are within the voltage range permissible for the network being protected.